<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
        <script src="../vue.js"></script>
    </head>

    <body>
        <div id="app">
            <h1>{{count}}</h1>
            <button @click="count++">count加一</button>
            <button @click="unWatch">取消监听</button>
        </div>
        <script>
            Vue.config.productionTip = false;

            const vm = new Vue({
                el: "#app",
                data() {
                    return {
                        count: 0,
                    };
                },
                methods: {
                    unWatch: function(){}
                },
            });
            vm.unWatch = vm.$watch(
                "count",
                function () {
                    console.log("改变了count");
                },
                {
                    immediate: true,
                }
            );
        </script>
    </body>
</html>
